Catalyst for propylene ammoxidation to acrylonitrile

ABSTRACT

Olefins such as propylene and isobutylene are converted to the corresponding unsaturated nitriles, acrylonitrile, and methacrylonitrile, respectively, by reacting a mixture of the olefin, ammonia, and molecular oxygen-containing gas in the presence of a catalyst containing the oxides of molybdenum, bismuth, iron, cobalt, nickel, and chromium, and either phosphorus or antimony or mixtures thereof, and an alkali metal or mixture thereof, and optionally one element selected from the group of an alkaline earth metal, a rare earth metal, niobium, thallium, arsenic, magnesium, zinc, cadmium, vanadium, boron, calcium, tin, germanium, manganese, tungsten, tellurium, or mixtures thereof.

This invention relates to an improved process and catalyst for theammoxidation of olefin-ammonia mixtures to unsaturated nitriles, andmore particularly to an improved process and catalyst for theammoxidation of propylene-ammonia and isobutylene-ammonia toacrylonitrile and methacrylonitrile, respectively. The ammoxidation isconducted in the presence of a catalyst comprising the oxides ofmolybdenum, bismuth, iron, cobalt, nickel, and chromium, and eitherphosphorus or antimony or mixtures thereof and an alkali metal ormixture thereof, and optionally one element selected from the group ofan alkaline earth metal, a rare earth metal, niobium, thallium, arsenic,magnesium, zinc, cadmium, vanadium, boron, calcium, tin, germanium,manganese, tungsten, tellurium, or mixtures thereof. It is alsoenvisioned that the catalyst of this invention would effectivelyfunction as a catalyst for fluid bed oxidation of propylene to acrolein.For example, the catalyst would function in the processes of U.S. Pat.Nos. 4,230,640 and 4,267,385 herein incorporated by reference.

There are many patents related to the production of acrylonitrile usinga bismuth-molybdenum-iron fluidized bed catalyst (e.g., 3,642,930). Inparticular, U.S. Pat. No. 3,911,089 issued Oct. 7, 1975 discloses aprocess for acrylonitrile production using a catalyst comprised of theoxides of molybdenum, and bismuth, and optionally iron, and optionallythe oxides of chromium, manganese, cobalt, nickel, zinc, cadmium, tin,tungsten, lead or mixtures thereof, and optionally thallium, a group IAor IIA element and optionally phosphorus, arsenic, antimony or mixturesthereof.

The catalyst employed in the process of this invention has high activityfor the production of unsaturated nitriles at a slightly lower reactiontemperature than is normally employed for this type of process, andcontinues efficient low temperature operation after aging. In additionto high activity for nitrile production, the catalyst has a number ofother important advantages that contribute greatly to the efficient andeconomic operation of the process. The catalyst has excellent redoxstability under the reaction conditions of the process. This permits theuse of low process air to olefin ratios and high weight hourly spacevelocities. The catalyst exhibits efficient ammonia utilization thusgreatly reducing the amount of unreacted ammonia appearing in thereactor effluent and thus lowering the amount of sulfuric acid requiredto neutralize the ammonia in the effluent. This results in improvementsin (1) the operation of the recovery section of the process and (2)pollution control. The use of lower operating temperatures favors longercatalyst life and minimizes effluent problems such as afterburning.Despite the lower reaction temperatures, per pass conversions to thenitrile product of 80 percent and above are obtained. A furtherimportant advantage associated with the catalyst of this invention isthe low cost of the essential catalytic components and the ease ofcatalyst preparation.

The reactants employed in producing the unsaturated nitriles of thisinvention are oxygen, ammonia, and an olefin having three carbon atomsin a straight chain such as propylene or isobutylene, and mixturesthereof.

The olefins may be in a mixture with paraffinic hydrocarbons, such asethane, propane, butane and pentane; for example, a propylene-propanemixture may constitute the feed. This makes it possible to use ordinaryrefinery streams without special separation, although the effectivenessof conversion would be diminished. Likewise, diluents such as nitrogenand oxides of carbon may be present in the reaction mixture withoutdeleterious effect.

In its preferred aspect, the process comprises contacting a mixturecomprising propylene or isobutylene, ammonia and oxygen with thecatalyst at an elevated temperature and at atmospheric or nearatmospheric pressure to produce acrylonitrile or methacrylonitrile. Mostpreferably, the process is directed to contacting propylene, ammonia andoxygen with a fluid bed catalyst at an elevated temperature to produceacrylonitrile.

Any source of oxygen may be employed in this process. For economicreasons, however, it is preferred that air be employed as the source ofoxygen. From a purely technical viewpoint, relatively pure molecularoxygen will give equivalent results. The molar ratio of oxygen to theolefin in the feed to the reaction vessel should be in the range of0.2:1 to 3.0 and a ratio of about 1.5 to 2.5 is preferred.

The molar ratio of ammonia to olefin in the feed to the reaction vesselmay vary between about 0.5:1 to 5:1, preferably 0.9:1 to 1.3:1. There isno real upper limit for the ammonia-olefin ratio, but there is generallyno reason to exceed a ratio of 1.3:1. At ammonia-olefin ratiosappreciably less than the stoichiometric ratio of 1:1, various amountsof oxygenated derivatives of the olefin will be formed. Outside theupper limit of this range only insignificant amounts of aldehydes andacids will be produced, and reduced amounts of nitriles will be producedat ammonia-olefin ratios below the lower limit of this range. It issurprising that within the ammonia-olefin range stated, maximumutilization of ammonia is obtained, and this is highly desirable. It isgenerally possible to recycle any unreacted olefin and unconvertedammonia.

In some cases water in the mixture fed to the reaction vessel improvesthe selectivity of the reaction and yield of nitrile. However, additionof water to the feed is not essential in this invention, inasmuch aswater is formed in the course of the reaction.

In general, the molar ratio of added water to olefin, when water isadded, is above about 0.25:1. Ratios on the order of 1:1 to 4:1 areparticularly desirable, but higher ratios may be employed, i.e., up toabout 10:1.

The reaction is carried out at a temperature within the range of fromabout 300° to about 600° C. The preferred temperature range is fromabout 380° to 500° C., especially preferred being from about 400° to480° C.

The pressure at which the reaction is conducted is another variable. Thereaction may be carried out at any pressure, however, preferably it iscarried out at about atmospheric or above atmospheric pressure (2 to 5atmospheres).

The apparent contact time is not critical, and contact times in therange of from 0.1 to about 50 seconds may be employed. The optimumcontact time will, of course, vary depending upon the olefin beingreacted, but in general, a contact time of from 1 to 15 seconds ispreferred.

Generally any apparatus of the type suitable for carrying outoxidation/ammoxidation reactions in the vapor phase may be employed inthe execution of this process. The process may be conducted eithercontinuously or intermittently. The catalyst bed may be a fixed-bedemploying a large particulate or pelleted catalyst or preferably, asocalled "fluidized" bed of catalyst may be employed. Any conventionalfluid ammoxidation reactor may be utilized in the practice of theprocess of the present invention. For example, the reactor described inU.S. Pat. No. 3,230,246, issued Jan. 18, 1966 incorporated herein byreference would be suitable in the practice of the present invention.Furthermore, conventional transfer line reactors may be used.

The reactor may be brought to the reaction temperature before or afterthe introduction of the reaction feed mixture. However, in a large scaleoperation it is preferred to carry out the process in a continuousmanner, and in such a system the recirculation of the unreacted olefinis contemplated. Periodic regeneration or reactivation of the catalystis also contemplated, and this may be accomplished, for example, bycontacting the catalyst with air at an elevated temperature.

The products of the reaction may be recovered by any of the methodsknown to those skilled in the art. One such method involves scrubbingthe effluent gases from the reactor with cold water or an appropriatesolvent to remove the products of the reaction. If desired, acidifiedwater can be used to absorb the products of the reaction and neutralizeunconverted ammonia. The ultimate recovery of the products may beaccomplished by conventional means. The efficiency of the scrubbingoperation may be improved when water is employed as the scrubbing agentby adding a suitable wetting agent in the water. Where molecular oxygenis employed as the oxidizing agent in this process, the resultingproduct mixture after the removal of the nitriles may be treated toremove carbon dioxide, with the remainder of the mixture containing theunreacted olefin and oxygen being recycled through the reactor. In thecase where air is employed as the oxidizing agent in lieu of molecularoxygen, the residual product after separation of the nitriles and othercarbonyl products may be scrubbed with a non-polar solvent, e.g., ahydrocarbon fraction in order to recover unreacted olefin, and in thiscase the remaining gases may be discarded. The addition of a suitableinhibitor to prevent polymerization of the unsaturated products duringthe recovery steps is also contemplated.

The catalyst useful in the process of the present invention is amixture, compound or possibly complex of the oxides of molybdenum,bismuth, iron, cobalt, nickel, chromium, and either phosphorus orantimony or mixtures thereof, and an alkali metal or mixture thereof,and optionally an alkaline earth, a rare earth metal, niobium, thallium,arsenic, magnesium, zinc, cadmium, vanadium, boron, calcium, tin,germanium, manganese, tungsten, tellurium or mixtures thereof. Thecomposition is characterized by the following empirical formula:

    Mo.sub.a Bi.sub.b Fe.sub.c Co.sub.d Ni.sub.e Cr.sub.f X.sub.g Y.sub.i Z.sub.j O.sub.x

wherein X is one or more of the elements selected from the groupcomprising phosphorus or antimony or mixture thereof, and Y is an alkalimetal or mixture thereof, and Z is an alkaline earth metal, a rare earthmetal, niobium, thallium, arsenic, magnesium, zinc, cadmium, vanadium,boron, calcium, tin, germanium, manganese, tungsten, tellurium ormixtures thereof, wherein (a) is a number from 12-14, (b) is a numberfrom 1-5, (c) is a number from 0.5-5, (d) and (e) are numbers from0.1-6, (f) is a number from 0.1-4, (g) is a number from 0.1-4, (i) is anumber from 0.1-2, (j) is a number from 0-3, and (k) is a numberdetermined by the valence requirements of the other elements present.Preferably (g) is a number from 0.75 to 3. Preferably, when Y is analkali metal other than sodium, (i) is a number from 0.1-1.5.Furthermore, the catalyst generally has a surface area of less than 100M² /g, preferably about 20 M² /g to about 50 M² /g.

The catalyst of this invention may be prepared by any of the numerousmethods of catalyst preparation which are known to those skilled in theart. For example, the catalyst may be manufactured by co-precipitatingthe various ingredients. The co-precipitated mass may then be dried andground to an appropriate size. Alternately, the co-precipitated materialmay be slurried and spray-dried in accordance with conventionaltechniques. The catalyst may be extruded as pellets or formed intospheres in oil as is well-known in the art. Alternatively, the catalystcomponents may be mixed with the support in the form of the slurryfollowed by drying, or they may be impregnated on silica or othersupports.

A particularly attrition-resistant form of the catalyst may be preparedby adding the support material to the catalyst in two stages, first bypreparing and heat-treating a mixture of active catalyst components andfrom 0 to 60% by weight of the total support material, followed byadding the remainder of the support material to the powdered form of theheat-treated catalyst.

The alkali metal may be introduced into the catalyst as an oxide or asany salt which upon calcination will yield the oxide. Preferred saltsare the nitrates which are readily available and easily soluble.

Bismuth may be introduced into the catalyst as an oxide or as any saltwhich upon calcination will yield the oxide. Preferred are thewater-soluble salts which are easily dispersible within the catalyst andwhich form stable oxides upon heat treating. A source for introducingbismuth is bismuth nitrate which has been dissolved in a dilute solutionof HNO₃. It is also especially preferred to dissolve bismuth nitrate ina metal nitrate melt.

To introduce the iron component into the catalyst one may use anycompound of iron which, upon calcination, will result in the oxides. Aswith the other elements, water-soluble salts are preferred for the easewith which they may be uniformly dispersed within the catalyst. Mostpreferred is ferric nitrate. Cobalt and nickel may be similarlyintroduced.

To introduce the molybdenum component, any molybdenum oxide such as thedioxide, trioxide, pentoxide, or sesquioxide may be used; more preferredis a hydrolyzable or decomposable molybdenum salt. The most preferredstarting material is ammonium heptamolybdate (AHM).

Phosphorus may be introduced as an alkali metal salt, an alkaline earthmetal salt or the ammonium salt, but is preferably introduced asphosphoric acid. The most preferred method is the use of phosphomolybdicacid which also introduces molybdenum.

Other elements may be introduced, starting with the metal, oxidizing themetal with an oxidizing acid such as nitric acid, and then incorporatingthe nitrate into the catalyst. Generally, however, the nitrates arereadily available and form a very convenient starting material.

Other variations in starting materials will suggest themselves to oneskilled in the art, particularly when the preferred starting materialsmentioned herein above are unsuited to the economics of largescalemanufacture. In general, any compounds containing the desired catalystcomponents may be used provided that they result in the oxides of theinstant catalyst upon heating to a temperature within the rangedisclosed hereinafter.

The catalyst can be employed without a support and will displayexcellent activity. The catalyst can also be combined with a support,and preferably it is combined with at least 10 percent up to about 90percent of the supporting compound by weight of the entire composition.Any known support materials can be used, such as, silica, alumina,zirconia, titania, ALUNDUM, silicon carbide, alumina-silica, theinorganic phosphates such as aluminum phosphate, silicates, aluminates,borates, carbonates, and materials such as pumice, montmorillonite, andthe like that are stable under the reaction conditions to be encounteredin the use of the catalyst. Aerosil may also be added to the supportmaterial. The preferred support is silica, which is added to the slurryduring the preparation of the catalyst in the form of silica sol orfumed silica. The level of support is usually in the range of 10-70%weight present. Preferably, the level of support is in the range of40-60% weight present.

The catalytic activity of the system is enhanced by heating at anelevated temperature. Generally, the catalyst mixture is spray dried ata temperature of between about 110° C. to 350° C. and then heat treatedin stages for from about one to twenty-four hours or more at atemperature of from about 260° to about 1000° C., preferably from300°-400° C. to 550°-700° C.

In general, calcination of the catalyst is achieved in less time athigher temperatures. The sufficiency of calcination at any given set ofconditions is ascertained by a spot test of a sample of the material forcatalytic activity. Calcination is best carried out in an open chamber,permitting circulation of air or oxygen, so that any oxygen consumed canbe replaced.

Further, pre-treatment or activation of the catalyst before use with areducing agent such as ammonia in the presence of a limited amount ofair at a temperature in the range of 260° to 540° C. is also used.

A preferred method of preparing the catalyst of this invention and amore complete description of the process of the invention can beobtained from the following examples. In addition to the production ofunsaturated nitriles, the catalyst of this invention is also useful forthe conversion of olefins, such as propylene and isobutylene, to thecorresponding unsaturated aldehydes and unsaturated carboxylic acids.

EXAMPLES 1 TO 8

The catalysts employed in the examples of this invention were preparedby the procedure described below.

EXAMPLE 1

Metal nitrates in the following order were melted together at ˜70° C. ina 400 ml beaker Fe(NO₃)₃.9H₂ O (65.08 g), Co(NO₃)₂.6H₂ O (121.89 g),Ni(NO₃)₂.6H₂ O (65.57 g)(AHM), Bi(NO₃).₃ 5H₂ O (65.24 g), KNO₃ (1.63 g).The (NH₄)₆ MoO₂₄.4H₂ O (184.85 g) was dissolved in 300 ml of distilledwater followed by the addition of the CrO₃ (8.05 g). To this solutionthe metal nitrates melt was added, followed by the 40% silica sol (625g). The resultant yellow slurry was heated by stirring at ˜90° C. for ˜3hours, then the slurry was spray dried. The obtained material wasdenitrified at 270° C. for 2 hours and at 425° C. for 2 hours and thenwas calcined at 580° C. for 2 hours in air.

EXAMPLE 2

Metal nitrates were melted at ˜70° C. in a 400 ml beaker in thefollowing order Fe(NO₃)₃.9H₂ O (65.10 g), Co(NO₃)₂.6H₂ O (121.93 g),Ni(NO₃).₂ 6H₂ O (65.6 g), Bi(NO₃).₃ 5H₂ O (65.20 g), KNO₃ (1.63 g). TheAHM (184.91 g) was dissolved in 300 ml of distilled water followed bythe addition of the CrO₃ (6.24 g) and 85% H₃ PO₄ (1.86 g). To thissolution the metal nitrates melt was added followed by the 40% silicasol (625 g). The resultant yellow slurry was heated by stirring at ˜90°C. for ˜3 hours, then the slurry was spray dried. The obtained materialwas denitrified at 270° C. for 2 hours and 425° C. for 2 hours and thenwas calcined in air at 580° C. for 2 hours.

EXAMPLE 3

Metal nitrates in the following order were melted together at ˜70° C. ina 400 ml beaker Fe(NO₃)₃.9H₂ O(65.1 g), Co(NO₃)₂.6H₂ O(121.9 g),Ni(NO₃)₂.6H₂ O (65.6 g), Bi(NO₃)₃.5H₂ O (65.3 g), KNO₃ (1.6 g). The AHM(184.9 g) was dissolved in 300 ml of distilled water followed by theaddition of the CrO₃ (4.0 g) and 85% H₃ PO₄ (4.65 g). To this solutionthe metal nitrate melt was added, followed by the 40% silica sol (625g). The resultant yellow slurry was heated by stirring at ˜90° C. for ˜3hours, then the slurry was spray dried. The obtained material wasdenitrified at 270° C. for 2 hours and 425° C. for 2 hours and then wascalcined in air at 580° C. for 2 hours.

EXAMPLE 4

Metal nitrates were melted together at ˜70° C. in a 400 ml beaker in thefollowing order Fe(NO₃)₃.9H₂ O (65.15 g), Co(NO₃)₂.6H₂ O (122.0 g),Ni(NO₃)₂.6H₂ O (63.3 g), Bi(NO₃)₃.5H₂ O (65.3 g), KNO₃ (0.8 ), Cs(NO₃)(1.26 g). The AHM (185.06 g) was dissolved in 300 ml of distilled waterfollowed by the addition of CrO₃ (4.03 g) and 85% H₃ PO₄ (4.65 g). Themetal nitrates melt was added to this solution followed by the 40%silica sol (625 g). The resultant yellow slurry was heated at ˜90° C.for ˜3 hours, then the slurry was spray dried. The obtained material wasdenitrified at 270° C. for 2 hours and 425° C. for 2 hours and then wascalcined at 580° C. for 2 hours in air.

EXAMPLE 5

Metal nitrates were melted together at ˜70° C. in a 400 ml beaker in thefollowing order Fe(NO₃)₃.9H₂ O (62.21 g), Co(NO₃)₂.6H₂ O (116.51 g),Ni(NO₃)₂.6H₂ O (62.68 g), Bi(NO₃)₃.5H₂ O (62.36 g), KNO₃ (1.56 ). TheAHM (176.7 g) was dissolved in 300 ml of distilled water followed by theaddition of CrO₃ (3.85 g) and 85% H₃ PO₄ (4.44 g). To this solution themetal nitrates melt was added followed by the Sb₂ O₃ (11.22 g) and the40% silica sol (625 g). The resultant yellow slurry was heated at ˜90°C. for ˜3 hours, then the slurry was spray dried. The obtained materialwas denitrified at 270° C. for 2 hours and 425° C. for 2 hours and thenwas calcined at 580° C. for 2 hours in air.

EXAMPLE 6

Metal nitrates were melted together at ˜70° C. in a 400 ml beaker in thefollowing order Fe(NO₃)₃.9H₂ O (59.3 g), Co(NO₃)₂.6H₂ O (111.0 g),Ni(NO₃)₂.6H₂ O (59.7 g), Bi(NO₃)₃.5H₂ O (59.4 g), KNO₃ (1.5 g). The AHM(168.4 g) was dissolved in 300 ml of distilled water followed by theaddition of CrO₃ (3.7 g) and 85% H₃ PO₄ (4.2 g). To this solution themetal nitrates melt was added followed by the Sb₂ O₃ (22.5 g) and the40% silica sol (625 g). The resultant yellow slurry was heated at ˜90°C. for ˜3 hours, then the slurry was spray dried. The obtained materialwas denitrified at 270° C. for 2 hours and 425° C. for 2 hours and thenwas calcined at 580° C. for 2 hours in air.

EXAMPLE 7

Metal nitrates were melted together at ˜70° C. in a 400 ml beaker in thefollowing order Fe(NO₃)₃.9H₂ O (62.22 g), Co(NO₃)₂.6H₂ O (116.54 g),Ni(NO₃)₂.6H₂ O (60.46 g), Bi(NO₃)₃.5H₂ O (62.38 g), KNO₃ (0.78 g) andCs(NO₃) (1.20 g). The AHM (176.75 g) was dissolved in 300 ml ofdistilled water followed by the addition of CrO₃ (3.85 g) and 85% H₃ PO₄(4.44 g). To this solution the metal nitrates melt was added followed bySb₂ O₃ (11.22 g) and 40% silica sol (625 g). The resultant yellow slurrywas heated at ˜90° C. for 3 hours, then the slurry was spray dried. Theobtained material was denitrified at 270° C. for 2 hours and 425° C. for2 hours and then was calcined at 580° C. for 2 hours in air.

EXAMPLE 8

Metal nitrates were melted together at ˜70° C. in a 400 ml beaker in thefollowing order Fe(NO₃)₃.9H₂ O(59.3 g), Co(NO₃)₂.6H₂ O(111.0 g),Ni(NO₃)₂.6H₂ O (57.6 g), Bi(NO₃)₃.5H₂ O (59.4 g), KNO₃ (0.7 g), andCs(NO₃) (1.2 g). The AHM (168.3 g) was dissolved in 300 ml of distilledwater followed by the addition of CrO₃ (3.7 g) and 85% H₃ PO₄ (4.2 g).To this solution the metal nitrates melt was added followed by Sb₂ O₃(22.4 g) and 40% silica sol (625 g). The resultant yellow slurry washeated at ˜90° C. for 3 hours, then the slurry was spray dried. Theobtained material was denitrified at 270° C. for 2 hours and 425° C. for2 hours and then was calcined at 580° C. for 2 hours in air.

In the examples given, percent conversion to the unsaturated nitrile isdefined as follows: ##EQU1##

Ammoxidation reactions carried out with catalyst compositions preparedby the method of Examples 1-8 and employing propylene as the hydrocarbonfeeds are summarized in Table I. Each reaction was run in a 40 cc fluidbed reactor. Each catalyst was initially reduced by NH₃ /N₂ at 440° C.for ten minutes. After a stabilization period of approximately 40 hours,samples were collected.

Reactor effluent was collected in bubble-type scrubbers containing acold HCl solution. Off-gas rate was measured with a soap filmmeter, andthe off-gas composition was determined at the end of the run with theaid of a Perkin-Elmer Model 154 gas chromatograph fitted with a splitcolumn gas analyzer.

At the end of the recovery run, the entire scrubber liquid was dilutedto approximately 200 grams with distilled water. A weighted amount ofMEK was used as an internal standard in a ˜50 gram aliquot of the dilutesolution.

A 6 micro liter sample was analyzed in a 5710 Hewlett-Packard gaschromatograph fitted with a flame ionization detector and a carbopakcolumn. The amount of HCN was determined by titration with AgNO₃.

                                      TABLE I                                     __________________________________________________________________________    Ex-                                                                           am-                              Temp.                                                                             AN   HCN  CO.sub.2                                                                           CO   Selectivity          ple                                                                              Catalyst Composition          (°C.)                                                                      (% ppc)                                                                            (% ppc)                                                                            (% ppc)                                                                            (% ppc)                                                                            to AN                __________________________________________________________________________                                                             (%)                  1  50%Mo.sub.13 Bi.sub.1.67 Fe.sub.2.0 Co.sub.5.2 Ni.sub.2.8 K.sub..2            Cr.sub.1.0 O.sub.x *50%SiO.sub.2                                                                            435 76.2 6.6  6.7  2.9  78.2                 2  50%Mo.sub.13 Bi.sub.1.67 Fe.sub.2.0 Co.sub.5.2 Ni.sub.2.8 K.sub..2            Cr.sub..8 P.sub..2 0.sub.x *50%SiO.sub.2                                                                    435 77.7 6.8  6.5  2.8  78.9                 3  50%Mo.sub.13 Bi.sub.1.67 Fe.sub.2.0 Co.sub.5.2 Ni.sub.2.8 K.sub..2            Cr.sub..5 P.sub..5 O.sub.x *50%SiO.sub.2                                                                    435 78.0 6.3  6.3  3.1  80.3                 4  50%Mo.sub.13 Bi.sub.1.67 Fe.sub.2.0 Co.sub.5.2 Ni.sub.2.8 K.sub..1            Cs.sub..08 Cr.sub..5 P.sub..5 O.sub.x *50%SiO.sub.2                                                         435 79.1 5.8  5.4  2.6  81.6                 5  50%Mo.sub.13 Bi.sub.1.67 Fe.sub.2.0 Co.sub.5.2 Ni.sub.2.8 K.sub..2            Cr.sub..5 P.sub..5 Sb.sub.1.0 O.sub.x *50%SiO.sub.2                                                         435 78.3 5.4  5.4  2.7  81.2                 6  50%Mo.sub.13 Bi.sub.1.67 Fe.sub.2.0 Co.sub.5.2 Ni.sub. 2.8 K.sub..2           Cr.sub..5 P.sub..5 Sb.sub.2.1 O.sub.x *50%SiO.sub.2                                                         430 80.2 5.5  6.0  2.9  81.8                 7  50%Mo.sub.13 Bi.sub.1.67 Fe.sub.2.0 Co.sub.5.2 Ni.sub.2.8 K.sub..1            Cs.sub..08 Cr.sub..5 P.sub..5 Sb.sub.1.0 O.sub.x *50%SiO.sub.2                                              435 79.4 3.9  5.7  2.7  82.6                 8  50%Mo.sub.13 Bi.sub.1.67 Fe.sub.2.0 Co.sub.5.2 Ni.sub.2.8 K.sub..1            Cs.sub..08 Cr.sub..5 P.sub..5 Sb.sub.2.1 O.sub.x *50%SiO.sub.2                                              435 80.2 5.0  5.3  2.4  83.2                 __________________________________________________________________________

What is claimed:
 1. A catalyst composition comprising a complex of thecatalytic oxides of molybdenum, bismuth, iron, cobalt, nickel, chromium,one or more of phosphorus and antimony, one or more of the groupcomprising alkali metals, and optionally one or more of an alkalineearth metal, a rare earth metal, niobium, thallium, arsenic, magnesium,zinc, cadmium, vanadium, boron, calcium, tin, germanium, manganese,tungsten, and/or tellurium having the formula:

    Mo.sub.a Bi.sub.b Fe.sub.c Co.sub.d Ni.sub.e Cr.sub.f X.sub.g Y.sub.i Z.sub.j O.sub.x

wherein X is a mixture of P and Sb; Y is an alkali metal or mixturesthereof; Z is an alkaline earth metal, a rare earth metal, Nb, Tl, As,Zn, Cd, V, B, Sn, Ge, Mn, W, Te or mixtures thereof; and wherein a is anumber from 12 to 14; b is a number from 1 to 5; c is a number from 0.5to 5; d and e are numbers from 0.1 to 6; f is a number from 0.1 to 4; gis a number from 0.1 to 4; i is a number from 0.1 to 2; j is a numberfrom 0 to 3; and x is a number determined by the valence requirements ofthe other elements present.
 2. The catalyst composition of claim 1,wherein said catalyst consists essentially of:

    Mo.sub.a Bi.sub.b Fe.sub.c Co.sub.d Ni.sub.e Cr.sub.f X.sub.g Y.sub.i Z.sub.j O.sub.x.


3. The composition of claim 1 wherein said catalyst consists of:

    Mo.sub.a Bi.sub.b Fe.sub.c Co.sub.d Ni.sub.e Cr.sub.f X.sub.g Y.sub.i Z.sub.j O.sub.x.


4. The composition of claim 1 wherein said catalyst is supported on acatalyst support material selected from the group consisting of silica,alumina or mixtures thereof.